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How Long Does Demerol Stay in Your System? (Blood, Urine, and More)

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Demerol is the brand name of a prescription opioid drug, meperidine. This brand version was the first approved formula for meperidine in the United States, initially manufactured by Sanofi Aventis Pharmaceuticals and approved by the U.S. Food and Drug Administration (FDA) in 1942.

When it was created, it was intended as an antispasmodic medication, but it was not found to be useful in this application. Over the years, meperidine has been applied to various levels of pain treatment, but because it has a rapid onset and the analgesic effects wear off quickly, it is no longer considered a safe or effective primary course of pain relief.

The American Pain Society (APS) does not recommend Demerol as the first choice for analgesia. They recommend limiting doses to 600 mg (milligrams) or less in a 24-hour period and using it to treat acute pain for no more than two days.

Demerol is more often found in hospital settings as preoperative analgesia, but there are versions of meperidine that can be taken at home. Because Demerol is very habit-forming, it is not recommended for consistent use for more than two days.

This opioid medication is a Schedule II drug according to the U.S. Drug Enforcement Administration (DEA). Tablet or syrup versions of this drug are consumed orally; at home, this medication should be taken every three or four hours, as needed to manage pain. Peak concentrations of the drug occur in one to two hours after it is taken. However, metabolites from meperidine remain in the body for hours, with only half of the drug being eliminated from the body as the analgesia wears off. This increases the risk of overdose from Demerol. 

Demerol’s Metabolites Last Longer Than the Drug’s Effects

Although the painkilling effects of Demerol last for only a few hours, metabolites from the liver and kidneys processing the medication can last for much longer, which increases the risk of side effects and overdose. In healthy adults, Demerol’s average half-life is between 2.5 and 4 hours, with the primary elimination method occurring through the kidneys as urine; however, in people who have liver damage or disease, elimination of the first metabolites of the drug can take between seven and 11 hours.

A second chemical called normeperidine is the result of the liver’s first round of metabolizing meperidine. Although the primary opioid analgesic effects break down as normeperidine appears in the body, this drug can interact with other substances for much longer than the body experiences effects. Normeperidine’s half-life is 15 to 20 hours, increasing the risk of side effects, including overdose, if more meperidine is consumed or other drugs are consumed on top of normeperidine, including antidepressants, anti-anxiety medication, and alcohol.

People with liver or kidney problems process the drug slower. About 80 percent remains bioavailable for longer, and normeperidine stays in the body for longer — 35 to 40 hours, on average.

Although the effects of normeperidine may not be apparent, it can cause side effects such as:

Side Efects

  • Tremors
  • Muscle twitching
  • Anxiety and paranoia
  • Hallucinations
  • Seizures

These symptoms indicate there is too much normeperidine in the body and that an overdose is occurring. Call 911 immediately because the individual requires emergency medical attention.

Because meperidine’s metabolite, normeperidine, remains in the body for a long time, drug testing relies on the presence of this chemical to determine if Demerol has been consumed. Drug detox and rehabilitation programs, workplaces, and hospitals may all use various forms of drug testing to determine if you are taking this drug as prescribed, if you have accidentally taken too much, or if you have relapsed back into substance abuse.

How Drug Tests Determine If You Abused Demerol

Several different kinds of drug tests can detect molecules in body tissues or waste after varying amounts of time. Fingernail and hair tests show if someone has consumed a drug at a point in the past and how long drug consumption lasted. Blood, saliva, and urine testing, in contrast, shows more active drug consumption, often within the past few hours to the past few days.

Urine tests: This approach to drug testing is the most widely used, especially in workplaces and substance abuse treatment programs, because it is minimally invasive and can detect the presence of drug metabolites for one to three days, depending on the substance. Random urine testing may be used by physicians to monitor their patients who have received prescription opioids like Demerol to manage pain, as a way to ensure that the individual is not taking more than prescribed and not taking the drug longer than prescribed.

Blood tests: This is a more invasive form of drug testing, so it is rarely the first approach, but it may be used by law enforcement or in other limited situations to determine if a person was intoxicated within a few minutes to hours of the test. If someone is suspected of being intoxicated, but metabolites are not picked up in a breathalyzer test for alcohol or a saliva test for other substances, the individual may be subject to a blood test for a more accurate determination.

Hair tests: Because of how hair grows from the scalp, this type of drug testing typically determines if drugs were consumed in the past 90 days (three months). Blood circulation, sweat, and naturally occurring skin oils leave metabolites of drugs on strands of hair as they grow. Tests can determine what kinds of drugs were consumed, so illicit substances or long-term drug abuse can be detected through these kinds of tests. However, hair tests will not show active drug consumption.


Saliva tests: While these are not the first approach to drug testing, saliva tests or oral fluid examinations can often show the presence of drug metabolites for up to 48 hours after use. Law enforcement may use this form of testing before a blood test, to determine if someone was intoxicated when they were arrested. Opioid drugs like heroin can be detected in oral fluid, so it is possible that Demerol can be detected in saliva samples, too.

Different drug tests may be administered depending on the situation. If you overdose on Demerol, for example, an emergency room may use blood tests to determine what substance you are suffering from and how much remains in your body. If you are in a detox program and appear intoxicated, you may be given a urine test for the program to determine if you have relapsed and returned to meperidine abuse.

Treatment programs use consistent drug testing — usually urine testing — to ensure sobriety and to determine if you need to return to detox or need additional help, like an inpatient program rather than an outpatient program.




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